The mechanisms by which various pathways of carbohydrate metabolism are regulated in oral bacteria continue to be under investigation. Special emphasis is currently placed on resolving 1) the mechanism by which Streptococcus salivarius exports the enzyme glucosyltransferase (GT) into the extracellular medium and 2) characterizing a factor(s) involved in the inactivation of a cell-associated fructosyltransferase. We have employed several techniques for altering the unsaturated:saturated fatty acid ratio in the cell membrane and then examined such modified cells for their ability to secrete GT. When the normal unsaturated:saturated fatty acid ratio of the lipid bilayer was increased 2-fold by growing the organism in the presence of Tween 80, the differential rate of extracellular GT production was very high. If the same membrane-unsaturated:saturated fatty acid ratio was imposed on cells by shifts in the growth temperature, however, the differential rate of GT production was very low. We conclude that the physical state of the bacterial membrane is not the sole factor involved in regulating GT secretion. Preliminary studies on the S. salivarius cell-associated FT indicate that this enzyme undergoes proteolytic digestion under conditions of amino acid limitation.